Explosive activator



Nov. 7, 1967 s. WALLACK ETAL 3,

EXPLOSIVE ACTIVATOR Filed Feb. 9, 1965 /N VEN 70/25, 5 714N157 MzmcK United States Patent 3,351,015 EXPLOSIVE ACTIVATOR Stanley Wallack, Jackson Heights, Laurence R. Alexander, Armonk, and James E. Oxley, New York, N.Y., assiguors to Leesona Corporation, Warwick, R.I., a corporation of Massachusetts Filed Feb. 9, 1965, Ser. No. 431,367 7 Claims. (Cl. 10270.2)

This invention relates to improved actuating devices. More particularly, the invention embraces explosive actuating devices of the type used in military and commercial detonators, electric switches, and the like.

Actuating devices based on the explosion of a small charge are known in the art. These devices are used extensively in military operations as detonators in weapons of war such as bombs, artillery shells, and numerous other objects of destruction. Additionally, they are used in civilian blasting operations employed in the excavation of road beds, construction of commercial buildings, and the like. Particularly when used in military weapons, these devices must be sufliciently sensitive to be triggered by a simple act expending only minor amounts of energy, In addition, however, the devices must be highly trustworthy from the standpoint of accidental discharge. As is apparent, the accidental discharge of a modern weapon could have devastating results.

In view of their importance to national defense, actuating devices of the type described have been the subject of considerable investigation and have reached a high degree of perfection. In spite of the fine state of development of such devices, an actuating or fuze system which is completely inert prior to initiation is still unavailable in the art. Electric initiators of the type known are sensitive to electromagnetic and radio frequency waves. Therefore, in the military, various means of alleviating the problem, including the use of low-pass radio frequency filter circuits, incorporated RF attenuators in the circuitry, and similar techniques, are being investigated. However, while the aforesaid devices and techniques are of some utility, all of the RF and EM hazard is not eliminated.

Although the problem of premature detonation of an explosive is primarily encountered in the military, the dif' ficulty is known in civilian operations as well. A wellrecognized hazard in civilian excavations is the accidental triggering of an explosive charge by the EM radiation and/or RF fields emitted by two-way radios in nearby cars or low-flying airplanes passing overhead.

Accordingly, a primary objective of the present invention is to provide an actuating device for use in detonators, explosive switches, explosive motors, and the like, which is completely inert prior to initiation of the actuating cycle. The device which is the object of this invention is designed to eliminate the hazards of accidental discharge due to EM radiation and RF fields and also oifers numerous other advantages over conventional electric actuators.

The presently described initiators are designed and operated in order that prior to the starting of the actuating cycle, accidental initiation cannot occur because the device does not contain an explosive material. According to the invention, during the activation, an explosive material is generated electrochemically by passage of a current through a suitable conductive medium. Inasmuch as an electrochemical reaction requires DC current, the device is completely insensitive to any RF or alternating current fields.

The herein described concept of generating the explosive material at the time of use can be applied to a variety of configurations and systems. The reaction may be a true electrochemical reaction or synthesis or simply the electrolytic decomposition of a substance to yield an explosive material or mixture. The conductive material can comprise a liquid, paste, gel, or solid. Final actuation of the explosive mixture can be accomplished by means of a heated filament, electric spark, or application of energy in other forms.

The drawing which forms a material part of this disclosure illustrates an actuating device according to the present invention. In the drawing, element 1 is a stainless steel housing which also serves as an electrical ground. Element 2 is a chamber containing the material which is to undergo electrochemical reaction to provide the explosive. Element 4 constitutes a second chamber leading from chamber 2 for collection of the explosive material when generated. When the actuating cycle is initiated, current is applied to electrode 3 which decomposes or otherwise electrochemically changes the material in chamber 2 forming the explosive material. As a continuation, or separate phase of the actuating cycle, current will be applied to electrode 6 in order that glow wire 5 will trigger the explosive material. The explosion will cause piston 7 to rupture membrane 8 which will trigger a further reaction. Membrane 8, while being sufiiciently strong to withstand the pressure of the explosive material prior to explosion, must be readily rupturable by the explosion of the charge. Suitable materials are the lightweight metals and plastics.

As will be apparent, numerous modifications are possible in the above cycle. For example, referring to the drawing, it is not essential to have the second chamber 4. It may be desirable from the standpoint of conserving space and to simplify construction to have the explosive material collect directly above the electrolyte and in this way eliminate the second chamber. Furthermore, it is not essential to have piston 7. The device, according to the invention, can be constructed to have rupturable membrane 8 in direct contact with explosive area 4, whether it be in a single chamber or a double chamber construction. In such a device, the explosive force will work directly on the membrane. Again, the explosive force may work directly upon a piston, with the motion of the piston closing one or more contacts for actuating further reactions. In such modifications, the membrane is not essential. Numerous other modifications in the design will be apparent to one skilled in the art, depending upon whether the reaction employed to generate the explosive material .is a true electrochemical reaction or merely an electrolytic decomposition.

In the operation of the presently described initiators, the device can be rigged in order that the closing of a single contact will initiate the formation of the explosive material and also the exploding of the material. In such an embodiment, the actuation of ignition means, such as glow wire 5, can be tied into a timing device in order that the wire will glow substantially immediately, or hours, or even days later to explode the material formed. Alternatively, the device can be wired in order that two separate and positive acts are necessary to actuate the mechanism. Thus, referring to the drawing, one act will initiate the reaction in the first or electrolyte chamber to form the explosive material and a second act will actuate the glow wire for setting olf the explosive material. An example of utility for the former mechanism will be in an electrical switch where a delayed action is intended. In the switch, the closing of a contact will provide current to electrode 3 starting the formation of the explosive material. A suitable time later, through a relay timer, current will be applied to electrode 6 which will cause glow wire 5 to explode the material so formed. The explosion will either break or close an electrical contact as desired. 0n the other hand, an actuating mechanism where two separate acts are necessary to complete the initiating cycle has utility'in weapons of war, such as nuclear warheads, where it is undesirable to charge the device until it is in its final position or installation. Thus, the actuating or arming mechanism will remain uncharged until the warhead is in its final location, at which time DC current will be applied to the electrochemical or electrolysis reaction to generate the explosive material. No current, however, will be applied to the electrode attached to the glow wire until the actual triggering of the warhead is desired. Such a device provides a completely dependable fuzing system.

Having described the invention in general terms, the following example is set forth to more particularly illustrate the invention. Referring to the drawing, five normal (5 N) potassium hydroxide was added to chamber 2. 0.8 amp. direct current at 3 volts was applied between the ground and electrode 3 for a period of three minutes. Hydrogen and oxygen was formed which collected in combustion chamber 4. Current was applied between the ground and electrode '6 causing glow wire 5 to ignite the explosive mixture of hydrogen and oxygen in chamber 4. The explosion created a pressure of greater than threehundred atmospheres upon detonation. In the embodiment described, the housing was stainless steel and the membrane a sheet of steel 0.5 mm. thick.

In the above example, rather than electrolyzing potassium hydroxide, materials such as Glaubers salt Naso an o aqueous hydrochloric acid or aqueous hydrobromic acid can be decomposed to provide, respectively, gaseous mixtures of hydrogen and oxygen, hydrogen and chlorine, or hydrogen and bromine. Furthermore, other electrochemical reactions can be employed to provide the explosive mixture. Additionally, as is apparent, other triggering devices can be employed in place of the glow wire, such as an electric spark.

As a further modification of the invention, the detonation pressure from the explosive mix can directly initiate a primary explosive, or this pressure may activate the explosive through an intermediate mechanical element such as a stab detonator.

Additionally, as noted hereinbefore, rather than employing the presently described actuator as a detonator, the mechanism can be used in explosive switches or the like. For example, the explosive force can work upon a plunger to activate an electrical switch. Similarly, the explosive force can be utilized to effect useful mechanical motion in an explosive motor of the caterpillar or dimple type. In practice, all electro-explosive devices can be actuated with the presently described mechanism, and the invention is not to be limited by the drawing or example set forth. In its most generic sense, the concept disclosed herein comprises the generation of an explosive in situ in a confined space and the explosion of this material to initiate a second reaction. Although emphasis is placed in the present specification upon the electrochemical formation of the explosive in view of its practical utility, it is possible to produce the explosive material by other means. Thus, two or more chemicals reactive with each other to form an explosive can be maintained out of contact with one another in a suitable chamber; and, at the time the explosive is to be effected, admixture of the chemicals can be accomplished, as for example with an electrical solenoid. Furthermore, the explosive can be formed by exposing a suitable material to gamma or beta radiation. Thus, as is apparent, numerous methods can be utilized in the preparation of the in situ explosive. A skilled technician, with the present disclosure as a guide, will be able to produce various embodiments without departing from the inventive concept herein disclosed. Such embodiments will be apparent to and are within the ability of one skilled in the art.

What is claimed and desired to be secured by Letter Patent.

1. A primary explosive comprising in combination a device for actuating said primary explosive comprising a housing constructed and arranged to form a chamber within said housing, a conductive material within said chamber, electrode means positions within said chamber to react upon said conductive material to form a secondary explosive, ignition means constructed and arranged in said chamber to ignite said secondary explosive, a 111pturable membrane in association with said chamber constructed and arranged to rupture upon ignition of said secondary explosive to actuate said primary explosive.

2. The actuating device of claim 1 wherein the ignition means is a glow wire attached to a means for providing DC current.

3. The actuating device of claim 1 wherein the ignition means comprises means for providing an electric spark.

4. The actuating device of claim 1 wherein the membrane is a lightweight metal.

5. The actuating device of claim 1 wherein the membrane is a plastic.

6. The actuating device of claim 1 wherein the conductive material is a solution of potassium hydroxide and the explosive is a mixture of hydrogen and oxygen.

7. The method of detonating a primary explosive comprising the steps of:

(1) reacting a conductive material electrochemically to produce a secondary explosive,

(2) collecting said secondary explosive in a confined area, and

(3) igniting said secondary explosive in said confined area to detonate said primary explosive.

References Cited UNITED STATES PATENTS 1,916,235 7/1933 Ruben 37 X 2,411,089 11/1946 Fredericks et al. 6037 X 3,002,458 10/1961 Haas 10270.2

BENJAMIN A. BORCHELT, Primary Examiner.

W. C. ROCH, Assistant Examiner. 

7. THE METHOD OF DETONATING A PRIMARY EXPLOSIVE COMPRISING THE STEPS OF: (1) REACTING A CONDUCTIVE MATERIAL ELECTROCHEMICALLY TO PRODUCE A SECONDARY EXPLOSIVE, (2) COLLECTING SAID SECONDARY EXPLOSIVE IN A CONFINED AREA, AND 